.alpha.-Amylases are a group of enzymes capable of hydrolyzing the .alpha.-1,4 glucosidic bonds of starch polymers. Various such amylases have been identified from divergent sources such as fungi, bacteria, plants and mammals. These enzymes are distinct from the others in that they may exhibit different pH optima, thermostabilities, calcium ion requirements, and the like. Such variations are believed to be due to the primary, secondary and tertiary structures of the enzyme, per se.
Because of the prevalence of these enzymes and their industrial importance a general method for identifying the presence of a gene encoding an .alpha.-amylase would be of substantial utility. This is particularly true where little or no information is available pertaining to the physical structure of the enzyme believed to be produced or when the organism in question does not produce sufficient amounts of the .alpha.-amylase to be detected or identified by standard screening procedures which are used for natural isolates of new enzymes. The present invention is directed to such a method whereby oligonucleotide probes of consensus DNA sequences are used to hybridize specifically to, and thereby identify, genes encoding .alpha.-amylase from a variety of sources.